linux-kernel - Re: [PATCH] flush icache before set_pte take6. [4/4] optimization for cpus other than montecito

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Message-ID: <46AEF518.4000002@bull.net>
Date:	Tue, 31 Jul 2007 10:38:48 +0200
From:	Zoltan Menyhart <Zoltan.Menyhart@...l.net>
To:	David Mosberger-Tang <dmosberger@...il.com>
Cc:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"linux-ia64@...r.kernel.org" <linux-ia64@...r.kernel.org>,
	"tony.luck@...el.com" <tony.luck@...el.com>,
	Christoph Lameter <clameter@....com>
Subject: Re: [PATCH] flush icache before set_pte take6. [4/4] optimization
 for cpus other than montecito

David Mosberger-Tang wrote:
> This seems crazy to me.  Flushing should occur according to the
> *architecture*, not model-by-model.  Even if we happen to get "lucky"
> on pre-Montecito CPUs, that doesn't justify such ugly hacks.  Or you
> really want to debug this *again* come next CPU?
> 
>   --david

O.K. let's say we flush by default: the global flag is set.

We can have a (short) list of the CPU models which do not require
this flush.

If all of the CPUs are on the list then clear the global flag. And:

static inline void sync_icache_dcache(pte_t pte) {
       if (pte_exec(pte) && global_flag)
               __sync_icache_dcache(pte);
}

Thanks,

Zoltan
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